Solar thermal reforming of methane feedstocks for hydrogen and syngas production—A review

It is currently accepted that at least for a transition period, solar-aided reforming of methane-containing gaseous feedstocks with natural gas (NG) being the first choice, can offer a viable route for fossil fuel decarbonization and create a transition path towards a “solar hydrogen- solar fuels” economy. Both industrially established traditional reforming concepts, steam and dry/carbon dioxide reforming, being highly endothermic can be rendered solar-aided and thus offer in principle a real possibility to lower the cost for introducing renewable hydrogen production technologies to the market by a combination of fossil fuels and solar energy. They also share similar technical issues considering linking of their key thermochemistry and thermodynamics to efficient exploitation of solar energy. In this perspective, the current article presents the development and current status of solar-aided reforming of gaseous methane-containing feedstocks, focussing in particular on the reactor technologies and concepts employed so far to couple the heat requirements of the methane reforming process to the underlying principles, intricacies and peculiarities of concentrated solar power (CSP) exploitation. A thorough literature review is presented, addressing practically the whole scale of solar reactors employed so far: from small-scale reactor prototypes often tested under simulated solar irradiation up to scaled-up reformer reactors tested on solar platform sites at the level of few hundreds of kilowatts. Having presented the current state-of-the-art of the technology, topics for future work are suggested and issues to help further commercialization are addressed.